being a hazbeen farmer I love torque to plough with,
high rev hp is no good as it uses lots of fuel , give me a plodder that sits on 1000 rpm up hill down dale without changing
A high rev 2600 engine dies quickly and needs a powershift gearbox.

Actually if you want to discuss politics I love to, just not in here. Join in this thread: http://forums.autosp...howtopic=106150 and we can go a couple rounds with the gloves off. Todd could definitely use a tag team partner for his wingnut Caliban Teaparty ranting. I might even do a little Obama bashing with you, but from a differing perspective. Just not in this forum.

Slider last time time I checked torque and power curves both contain "time" information.

You and Slider are describing two different things. A torque curve contains time infomation only because the value is plotted x-y vs rpm. The torque value itself contains no time reference: 200 lb-ft. What he wrote was perfectly accurate. You just changed the subject. I see you went from zero to talking straight past people in 1.5 posts. Most impressive.

You and Slider are describing two different things. A torque curve contains time infomation only because the value is plotted x-y vs rpm. The torque value itself contains no time reference: 200 lb-ft. What he wrote was perfectly accurate. You just changed the subject. I see you went from zero to talking straight past people in 1.5 posts. Most impressive.

Let's say Y is power and Y' is torque

Yes it cointains: Torque value Y' is achieved at X RPM. Not at X +100 RPM neither at X-100 RPM. So Y' is a function of X.

The toque curve(Y') is the first derivative of the power curve (Y) along time (X).

Serious, really, I just can't figure out why this shit is so complicated. People never learned calculus?

Your torque wrench will deliver torque in a static maner. A stopped engine delivers no torque, it will only deliver torque when it's spinning. And at NTP, at one given speed it will always deliver the same amount of torque.

You and Slider are describing two different things. A torque curve contains time infomation only because the value is plotted x-y vs rpm. The torque value itself contains no time reference: 200 lb-ft. What he wrote was perfectly accurate. You just changed the subject. I see you went from zero to talking straight past people in 1.5 posts. Most impressive.

Slider responded to consequtive posts by myself and Saudoso. If you take the time to view all three posts you will see that it was Slider who posted out of context. . . as you have now done in typical provocative style.

Agreed, gruntguru was talking about "torque curves" and "power curves", and saudoso's "they" referred to "torque curves" and "power curves", which obviously contain time information. bigleagueslider's response was talking about something else but appeared to be trying to contradict saudoso, which it did not. The comment was as useless and clueless as his other political one.

Going back to Chapter 1 in this never ending story,the thing I took away was you follow the powertrain back to the combustion chamber..spark plug fires...FORCE is produced.Then you need the conrod and crank to turn that into torque...then you need that to be repeated as often as possible to make power.Once you have force you can get torque,keep that coming for a period of time you have power.Are they the same thing ? Not really !

The thing is, with an ICE if you don't have speed you don't have force/torque. It's a moving machine that needs speed to transform energy. And oddly enough, with throttles 100% open, for a given speed it will deliver always the same torque.

So you have a device that produces no force if it has no speed. And for each given speed it will always deliver the same given torque. How can you think of disregarding speed every time you mention torque?

Torque=f(s)
Power=f(s)*s

C'mon guys, it's not THAT complicated. Pretty much high school physics and calculus. First year college at most.

Going back to Chapter 1 in this never ending story,the thing I took away was you follow the powertrain back to the combustion chamber..spark plug fires...FORCE is produced.Then you need the conrod and crank to turn that into torque...then you need that to be repeated as often as possible to make power.Once you have force you can get torque,keep that coming for a period of time you have power.Are they the same thing ? Not really !

In a thermodynamic analysis you start even further back - with PRESSURE. As with force and torque, you don't get anything useful (work or mechanical energy) until something moves. So work is the integral of pressure wrt change in volume. Much the same as force wrt displacement and torque wrt angle.

Power of course is the rate of work production.

EDIT. There is an error that pops up pretty frequently on this forum - that torque and power are related by "time". It is actually "angular velocity", ("rate of change of angle" or rotation per unit time) that relates the two. To summarise:

In a thermodynamic analysis you start even further back - with PRESSURE. As with force and torque, you don't get anything useful (work or mechanical energy) until something moves. So work is the integral of pressure wrt change in volume. Much the same as force wrt displacement and torque wrt angle.

Power of course is the rate of work production.

EDIT. There is an error that pops up pretty frequently on this forum - that torque and power are related by "time". It is actually "angular velocity", ("rate of change of angle" or rotation per unit time) that relates the two. To summarise:

True enough,but in a cylinder the expanding gas force may indeed spread out over the piston crown as a certain pressure p.s.i. but comes together again in the conrod as a force ?

Exactly, the piston's purpose in life is to convert pressure into force. The work done by the expanding gas on the piston crown can only be expressed as the integral of P.dV however because some of this work is lost to friction on the cylinder walls. So work done by the piston on the conrod (Integral of F.dS) is less than the Integral of P.dV (Having said that, force on the piston crown is of course P x Area of cylinder)

A stopped engine delivers no torque, it will only deliver torque when it's spinning.

Not so. You grab hold of the crank handle of the Model T with the engine stopped. Observe while I work the spark lever and break your arm for you.

Depending how you look at it, there is a little something in what you say. However, it only holds for some conditions and only for internal combustion engines. Other prime movers -- including electric motors, steam engines, and turbines -- develop torque and perform work at zero rpm. So what was your point about the universal properties of torque and power again? I suppose you will note that a piston engine must be free to operate in order to... umm, operate. Congratulations on the keen observation.

Not so. You grab hold of the crank handle of the Model T with the engine stopped. Observe while I work the spark lever and break your arm for you.

Depending how you look at it, there is a little something in what you say. However, it only holds for some conditions and only for internal combustion engines. Other prime movers -- including electric motors, steam engines, and turbines -- develop torque and perform work at zero rpm. So what was your point about the universal properties of torque and power again? I suppose you will note that a piston engine must be free to operate in order to... umm, operate. Congratulations on the keen observation.

You look ath the beggining of my post and you will read "The thing is, with an ICE...". And nothing produces work if there is no movement.

GG and I said that the "Torque Curve" and the "Power Curve" of an ICE represent the one and same information.

Pay attention to the statements:

QUOTE (gruntguru @ Mar 23 2012, 09:32) But a "Torque Curve" is as good as a "power Curve".QUOTE (saudoso @ Mar 23 2012, 21:48) They represent the same information and can be directly calculated one from the other, so I guess they are pretty much the same.

Now someone please tell me how you get an engine, attach it to a bench, run it and plot the torque and power curves?

If someone presents me a way to do it other than plotting the toqrue/RPM curve and then multipling it by the RPM to get the power/RPM curve I'll eat my socks.

If your observation only applies to ICEs, then you aren't discussing the properties of torque and power. You are only discussing the properties of ICEs.

Power and torque curves of ICEs. Wasn't this the point being discussed?

You still let slip the fact that for any other deice you mentioned there is no work if there is no movement, so there is no work if there is not speed and then we can conclude that there is no work if there is no time variable included. There is only stactitc force. Like a beam or colum or a rusted door hinge can produce.

You still let slip the fact that for any other deice you mentioned there is no work if there is no movement, so there is no work if there is not speed and then we can conclude that there is no work if there is no time variable included. There is only stactitc force. Like a beam or colum or a rusted door hinge can produce.

Your assertion is not true.

1. We can attach an electric motor to a shaft and, by manipulating the input, use it to stabilize varying and opposing loads on the shaft -- i.e. a trim tab. The shaft remains stationary and the motor remains at zero rpm yet it exerts torque, performs work, and produces power, which can be proven instrumentally with metaphysical certainty.

2. A tricycle is sitting on a ramp. I place my hand upon the circumference of the front wheel to prevent the tricycle from rolling downhill. I am producing torque, work, and power.

I'm sure you can think of many more examples yourself.

Personally, I find it confusing and awkward to have one set of physical terms, concepts, and laws that apply to internal combustion engines, another for external combustion engines, another for electric motors, yet another for tricycles on inclines, etc. It is my view that if we need more than the one set we already have, we are doing it wrong.

1. We can attach an electric motor to a shaft and, by manipulating the input, use it to stabilize varying and opposing loads on the shaft -- i.e. a trim tab. The shaft remains stationary and the motor remains at zero rpm yet it exerts torque, performs work, and produces power, which can be proven instrumentally with metaphysical certainty.

2. A tricycle is sitting on a ramp. I place my hand upon the circumference of the front wheel to prevent the tricycle from rolling downhill. I am producing torque, work, and power.

I'm sure you can think of many more examples yourself.

Personally, I find it confusing and awkward to have one set of physical terms, concepts, and laws that apply to internal combustion engines, another for external combustion engines, another for electric motors, yet another for tricycles on inclines, etc. It is my view that if we need more than the one set we already have, we are doing it wrong.

1. Wrong. The motor will be probably acted on by a derivative integrative controller of the tab position, and it will require minimal, but still some movement for the force to be adjusted and the position re established.

2. You are confusing burning energy to produce force with producing work and power. You're only dissipating energy and contributing to the universe's entropy raise. If there is no movement there is not work and no power. You are being silly by burning your arm to accomplish what a wood wedge would do.

I'm not using separate concepts. Just stating the peculiar characteristis of two empiric diagrams (the torque and the power curves) when related to a specific kind of machine.

But I guess the comparison is not fair. I did study English after school for I guess 5 years as a teenager, but I've been working with american companies/software and watching american movies all my life. Not counting how much I learn here or reading English in the Kindle. And there is always google spell checking with it's helping hand.

1. We can attach an electric motor to a shaft and, by manipulating the input, use it to stabilize varying and opposing loads on the shaft -- i.e. a trim tab. The shaft remains stationary and the motor remains at zero rpm yet it exerts torque, performs work, and produces power, which can be proven instrumentally with metaphysical certainty.

2. A tricycle is sitting on a ramp. I place my hand upon the circumference of the front wheel to prevent the tricycle from rolling downhill. I am producing torque, work, and power.

Your two examples suggest that work can be performed and power produced in a stationary shaft which of course is not true.

2. A tricycle is sitting on a ramp. I place my hand upon the circumference of the front wheel to prevent the tricycle from rolling downhill. I am producing torque, work, and power.

A book I was given at the age of 8 illustrated this in a pair of pictures. A clown on the left is attempting unsuccesfully to lift a chair that is nailed to floor, pulling upwards with all his might. A clown on the right lifts a feather from the floor. The caption, "which clown is doing more work?" At the time the answer seemed most unfair to the chap on the left, but the physics is indisputable. Semantics, on the other hand...